Low complex deblocking filter decisions

ABSTRACT

The present disclosure relates to deblocking filtering, which may be advantageously applied for block-wise encoding and decoding of images or video signals. In particular, the present disclosure relates to an improved memory management in an automated decision on whether to apply or skip deblocking filtering for a block and to selection of the deblocking filter. The decision is performed on the basis of a segmentation of blocks in such a manner that memory usage is optimized. Preferably, the selection of appropriate deblocking filters is improved so as to reduce computational expense.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation application of PCT Patent Application No.PCT/EP2012/067433 filed on Sep. 6, 2012, designating the United Statesof America, which is based on and claims priority of U.S. ProvisionalPatent Application No. 61/532,793 filed on Sep. 9, 2011. The entiredisclosures of the above-identified applications, including thespecifications, drawings and claims are incorporated herein by referencein their entirety.

FIELD

One or more exemplary embodiments disclosed herein relate generally tothe filtering of images. In particular, one or more exemplaryembodiments disclosed herein relate to deblocking filtering and todecisions as to whether enable or disable deblocking filtering for animage region.

BACKGROUND

At present, the majority of standardized video coding algorithms arebased on hybrid video coding. Hybrid video coding methods typicallycombine several different lossless and lossy compression schemes inorder to achieve the desired compression gain. Hybrid video coding isalso the basis for ITU-T standards (H.26x standards such as H.261,H.263) as well as ISO/IEC standards (MPEG-X standards such as MPEG-1,MPEG-2, and MPEG-4). The most recent and advanced video coding standardis currently the standard denoted as H.264/MPEG-4 advanced video coding(AVC) which is a result of standardization efforts by joint video team(JVT), a joint team of ITU-T and ISO/IEC MPEG groups. This codec isbeing further developed by Joint Collaborative Team on Video Coding(JCT-VC) under a name High-Efficiency Video Coding (HEVC), aiming, inparticular at improvements of efficiency regarding the high-resolutionvideo coding.

A video signal input to an encoder is a sequence of images calledframes, each frame being a two-dimensional matrix of pixels. All theabove-mentioned standards based on hybrid video coding includesubdividing each individual video frame into smaller blocks consistingof a plurality of pixels. The size of the blocks may vary, for instance,in accordance with the content of the image. The way of coding may betypically varied on a per block basis. The largest possible size forsuch a block, for instance in HEVC, is 64×64 pixels. It is then calledthe largest coding unit (LCU). In H.264/MPEG-4 AVC, a macroblock(usually denoting a block of 16×16 pixels) was the basic image element,for which the encoding is performed, with a possibility to furtherdivide it in smaller subblocks to which some of the coding/decodingsteps were applied.

Typically, the encoding steps of a hybrid video coding include a spatialand/or a temporal prediction. Accordingly, each block to be encoded isfirst predicted using either the blocks in its spatial neighborhood orblocks from its temporal neighborhood, i.e. from previously encodedvideo frames. A block of differences between the block to be encoded andits prediction, also called block of prediction residuals, is thencalculated. Another encoding step is a transformation of a block ofresiduals from the spatial (pixel) domain into a frequency domain. Thetransformation aims at reducing the correlation of the input block.Further encoding step is quantization of the transform coefficients. Inthis step the actual lossy (irreversible) compression takes place.Usually, the compressed transform coefficient values are furthercompacted (losslessly compressed) by means of an entropy coding. Inaddition, side information necessary for reconstruction of the encodedvideo signal is encoded and provided together with the encoded videosignal. This is for example information about the spatial and/ortemporal prediction, amount of quantization, etc.

SUMMARY Technical Problem

However, the deblocking filtering used in the conventional image codingmethod and image decoding method has a problem in that memory cannot beeffectively used.

Solution to Problem

In one general aspect, the techniques disclosed here feature a methodfor deblocking filtering of image blocks of pixels, including the stepsof: dividing each of a first and a second block that are separated by afirst boundary into at least two segments along a line that isperpendicular to said first boundary, and judging whether or not toapply a deblocking filter to pixels adjacent to the first boundary ofthe first and the second block, wherein the judgment is individuallyperformed for a pair of adjacent segments on both sides of the firstboundary using sample pixels in the pair of adjacent segments, such thatno pixels belonging to other segments are used in the judgment, and thedivision of the blocks into segments is performed such that a segment ofa block includes all pixels of the block required for judging whether ornot to apply a deblocking filter and/or a selection of the deblockingfilter for deblocking pixels adjacent to a second boundary between saidblock and a third block, wherein the second boundary is perpendicular tothe first boundary.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Additional benefits and advantages of the disclosed embodiments will beapparent from the Specification and Drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the Specification and Drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

Advantageous Effects

A method for deblocking filtering of images according to one or moreexemplary embodiments or features disclosed herein provide an efficientdeblocking filtering approach wherein the efficiency of memory usage isimproved.

BRIEF DESCRIPTION OF DRAWINGS

These and other advantages and features will become apparent from thefollowing description thereof taken in conjunction with the accompanyingDrawings, by way of non-limiting examples of embodiments disclosedherein.

FIG. 1 is a block diagram illustrating an example of a video encoder.

FIG. 2 is a block diagram illustrating an example of a video decoder.

FIG. 3 is another block diagram illustrating an example of a videoencoder.

FIG. 4A is a schematic drawing illustrating the application of ahorizontal deblocking filter.

FIG. 4B is a schematic drawing illustrating the application of avertical deblocking filter.

FIG. 5 is a schematic drawing illustrating a decision whether to applyor not to apply deblocking and a selection of a deblocking filter.

FIG. 6A is a schematic drawing illustrating deblocking operationsperformed by a strong filter.

FIG. 6B is a schematic drawing illustrating deblocking operationsperformed by a weak filter.

FIG. 7 is a flow diagram illustrating a sequence of deblocking decisionsto be subsequently taken from an exemplary block of eight rows/columns.

FIG. 8 is a schematic drawing illustrating samples of pixels used toperform a first kind of decisions in the flow chart of FIG. 7.

FIG. 9 is a schematic drawing illustrating pixel samples employed forperforming a second kind of decisions in the flow chart of FIG. 7.

FIG. 10 is a schematic drawing illustrating pixel samples used toperform a third kind of decisions in the flow chart of FIG. 7 for thecase of horizontal filtering of vertical edges.

FIG. 11 is a schematic drawing illustrating pixel samples used toperform horizontal deblocking filtering for vertical edges.

FIG. 12 is a schematic drawing illustrating sample pixels used toperform the third kind of decisions in the flow chart of FIG. 7 for thecase of vertical filtering of horizontal edges.

FIG. 13 is a schematic drawing illustrating sample pixels used toperform the vertical deblocking filtering for horizontal edges.

FIG. 14 is an illustration of samples, which may be modified by thehorizontal deblocking of vertical edges.

FIG. 15 is an illustration of samples modified by the horizontaldeblocking of vertical edges.

FIG. 16 is a an illustration of samples modified by either thehorizontal or vertical deblocking.

FIGS. 17A-17D are schematic drawings illustrating a problem occurring inthe parallel performance of the first and second kind of decisions ofthe flow chart of FIG. 7 for horizontal and vertical filtering, and thebasic idea of overcoming the problem in accordance with the presentdisclosure.

FIG. 18 is a scheme illustrating that the dependencies in the deblockingaccording to the present disclosure are limited to 8×8 samples.

FIGS. 19A and 19B are schematic drawings illustrating a specific exampleof a decision on whether to apply or not to apply a deblocking filter inaccordance with an embodiment of the present disclosure.

FIGS. 20A and 20B are schematic drawings illustrating exemplarysolutions of the decision for selecting an appropriate deblocking filterin accordance with an embodiment of the present disclosure.

FIGS. 21A and 21B are schematic drawings illustrating an alternativeexemplary solution of the decision for selecting an appropriatedeblocking filter in accordance with an embodiment of the presentdisclosure.

FIGS. 22A and 22B are schematic block diagrams illustrating a memoryaccess problem occurring when performing the decision whether to applyor not to apply a deblocking filter.

FIGS. 23A and 23B are schematic drawings illustrating a solution of thememory access problem illustrated in FIGS. 22A and B.

FIG. 24 shows an overall configuration of a content providing system forimplementing content distribution services.

FIG. 25 shows an overall configuration of a digital broadcasting system.

FIG. 26 shows a block diagram illustrating an example of a configurationof a television.

FIG. 27 shows a block diagram illustrating an example of a configurationof an information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk.

FIG. 28 shows an example of a configuration of a recording medium thatis an optical disk.

FIG. 29A shows an example of a cellular phone.

FIG. 29B is a block diagram showing an example of a configuration of acellular phone.

FIG. 30 illustrates a structure of multiplexed data.

FIG. 31 schematically shows how each stream is multiplexed inmultiplexed data.

FIG. 32 shows how a video stream is stored in a stream of PES packets inmore detail.

FIG. 33 shows a structure of TS packets and source packets in themultiplexed data.

FIG. 34 shows a data structure of a PMT.

FIG. 35 shows an internal structure of multiplexed data information.

FIG. 36 shows an internal structure of stream attribute information.

FIG. 37 shows steps for identifying video data.

FIG. 38 shows an example of a configuration of an integrated circuit forimplementing the moving picture coding method and the moving picturedecoding method according to each of embodiments.

FIG. 39 shows a configuration for switching between driving frequencies.

FIG. 40 shows steps for identifying video data and switching betweendriving frequencies.

FIG. 41 shows an example of a look-up table in which video datastandards are associated with driving frequencies.

FIG. 42A is a diagram showing an example of a configuration for sharinga module of a signal processing unit.

FIG. 42B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS Underlying Knowledge Forming Basis of thePresent Disclosure

FIG. 1 is an example of a typical H.264/MPEG-4 AVC and/or HEVC videoencoder 100. A subtractor 105 first determines differences e between acurrent block to be encoded of an input video image (input signal s) anda corresponding prediction block ŝ, which is used as a prediction of thecurrent block to be encoded. The prediction signal may be obtained by atemporal or by a spatial prediction 180. The type of prediction can bevaried on a per frame basis or on a per block basis. Blocks and/orframes predicted using temporal prediction are called “inter”-encodedand blocks and/or frames predicted using spatial prediction are called“intra”-encoded. Prediction signal using temporal prediction is derivedfrom the previously encoded images, which are stored in a memory. Theprediction signal using spatial prediction is derived from the values ofboundary pixels in the neighboring blocks, which have been previouslyencoded, decoded, and stored in the memory. The difference e between theinput signal and the prediction signal, denoted prediction error orresidual, is transformed 110 resulting in coefficients, which arequantized 120. Entropy encoder 190 is then applied to the quantizedcoefficients in order to further reduce the amount of data to be storedand/or transmitted in a lossless way. This is mainly achieved byapplying a code with code words of variable length wherein the length ofa code word is chosen based on the probability of its occurrence.

Within the video encoder 100, a decoding unit is incorporated forobtaining a decoded (reconstructed) video signal s′. In compliance withthe encoding steps, the decoding steps include dequantization andinverse transformation 130. The so obtained prediction error signal e′differs from the original prediction error signal due to thequantization error, called also quantization noise. A reconstructedimage signal s′ is then obtained by adding 140 the decoded predictionerror signal e′ to the prediction signal ŝ. In order to maintain thecompatibility between the encoder side and the decoder side, theprediction signal ŝ is obtained based on the encoded and subsequentlydecoded video signal which is known at both sides the encoder and thedecoder.

Due to the quantization, quantization noise is superposed to thereconstructed video signal. Due to the block-wise coding, the superposednoise often has blocking characteristics, which result, in particularfor strong quantization, in visible block boundaries in the decodedimage. Such blocking artifacts have a negative effect upon human visualperception. In order to reduce these artifacts, a deblocking filter 150is applied to every reconstructed image block. The deblocking filter isapplied to the reconstructed signal s′. For instance, the deblockingfilter of H.264/MPEG-4 AVC has the capability of local adaptation. Inthe case of a high degree of blocking noise, a strong (narrow-band) lowpass filter is applied, whereas for a low degree of blocking noise, aweaker (broad-band) low pass filter is applied. The strength of the lowpass filter is determined by the prediction signal ŝ and by thequantized prediction error signal e′. Deblocking filter generallysmoothes the block edges leading to an improved subjective quality ofthe decoded images. Moreover, since the filtered part of an image isused for the motion compensated prediction of further images, thefiltering also reduces the prediction errors, and thus enablesimprovement of coding efficiency.

After a deblocking filter, a sample adaptive offset 155 and/or adaptiveloop filter 160 may be applied to the image including the alreadydeblocked signal s″. Whereas the deblocking filter improves thesubjective quality, sample adaptive offset (SAO) and ALF aim atimproving the pixel-wise fidelity (“objective” quality). In particular,SAO adds an offset in accordance with the immediate neighborhood of apixel. The adaptive loop filter (ALF) is used to compensate imagedistortion caused by the compression. Typically, the adaptive loopfilter is a Wiener filter with filter coefficients determined such thatthe mean square error (MSE) between the reconstructed s′ and sourceimages s is minimized. The coefficients of ALF may be calculated andtransmitted on a frame basis. ALF can be applied to the entire frame(image of the video sequence) or to local areas (blocks). An additionalside information indicating which areas are to be filtered may betransmitted (block-based, frame-based or quadtree-based).

In order to be decoded, inter-encoded blocks require also storing thepreviously encoded and subsequently decoded portions of image(s) in thereference frame buffer 170. An inter-encoded block is predicted 180 byemploying motion compensated prediction. First, a best-matching block isfound for the current block within the previously encoded and decodedvideo frames by a motion estimator. The best-matching block then becomesa prediction signal and the relative displacement (motion) between thecurrent block and its best match is then signalized as motion data inthe form of three-dimensional motion vectors within the side informationprovided together with the encoded video data. The three dimensionsconsist of two spatial dimensions and one temporal dimension. In orderto optimize the prediction accuracy, motion vectors may be determinedwith a spatial sub-pixel resolution e.g. half pixel or quarter pixelresolution. A motion vector with spatial sub-pixel resolution may pointto a spatial position within an already decoded frame where no realpixel value is available, i.e. a sub-pixel position. Hence, spatialinterpolation of such pixel values is needed in order to perform motioncompensated prediction. This may be achieved by an interpolation filter(in FIG. 1 integrated within Prediction block 180).

For both, the intra- and the inter-encoding modes, the differences ebetween the current input signal and the prediction signal aretransformed 110 and quantized 120, resulting in the quantizedcoefficients. Generally, an orthogonal transformation such as atwo-dimensional discrete cosine transformation (DCT) or an integerversion thereof is employed since it reduces the correlation of thenatural video images efficiently. After the transformation, lowerfrequency components are usually more important for image quality thenhigh frequency components so that more bits can be spent for coding thelow frequency components than the high frequency components. In theentropy coder, the two-dimensional matrix of quantized coefficients isconverted into a one-dimensional array. Typically, this conversion isperformed by a so-called zig-zag scanning, which starts with theDC-coefficient in the upper left corner of the two-dimensional array andscans the two-dimensional array in a predetermined sequence ending withan AC coefficient in the lower right corner. As the energy is typicallyconcentrated in the left upper part of the two-dimensional matrix ofcoefficients, corresponding to the lower frequencies, the zig-zagscanning results in an array where usually the last values are zero.This allows for efficient encoding using run-length codes as a partof/before the actual entropy coding.

The H.264/MPEG-4 H.264/MPEG-4 AVC as well as HEVC includes twofunctional layers, a Video Coding Layer (VCL) and a Network AbstractionLayer (NAL). The VCL provides the encoding functionality as brieflydescribed above. The NAL encapsulates information elements intostandardized units called NAL units according to their furtherapplication such as transmission over a channel or storing in storage.The information elements are, for instance, the encoded prediction errorsignal or other information necessary for the decoding of the videosignal such as type of prediction, quantization parameter, motionvectors, etc. There are VCL NAL units containing the compressed videodata and the related information, as well as non-VCL units encapsulatingadditional data such as parameter set relating to an entire videosequence, or a Supplemental Enhancement Information (SEI) providingadditional information that can be used to improve the decodingperformance.

FIG. 2 illustrates an example decoder 200 according to the H.264/MPEG-4AVC or HEVC video coding standard. The encoded video signal (inputsignal to the decoder) first passes to entropy decoder 290, whichdecodes the quantized coefficients, the information elements necessaryfor decoding such as motion data, mode of prediction etc. The quantizedcoefficients are inversely scanned in order to obtain a two-dimensionalmatrix, which is then fed to inverse quantization and inversetransformation 230. After inverse quantization and inversetransformation 230, a decoded (quantized) prediction error signal e′ isobtained, which corresponds to the differences obtained by subtractingthe prediction signal from the signal input to the encoder in the caseno quantization noise is introduced and no error occurred.

The prediction signal is obtained from either a temporal or a spatialprediction 280. The decoded information elements usually further includethe information necessary for the prediction such as prediction type inthe case of intra-prediction and motion data in the case of motioncompensated prediction. The quantized prediction error signal in thespatial domain is then added with an adder 240 to the prediction signalobtained either from the motion compensated prediction or intra-frameprediction 280. The reconstructed image s′ may be passed through adeblocking filter 250, sample adaptive offset processing 255, and anadaptive loop filter 260 and the resulting decoded signal is stored inthe memory 270 to be applied for temporal or spatial prediction of thefollowing blocks/images.

A further illustration of an exemplary hybrid video encoder is shown inFIG. 3. The encoder of FIG. 3 differs from the encoder of FIG. 1 in thatdeblocking filter 150 of FIG. 1 has been subdivided in a filter 350 afor horizontal deblocking of vertical edges and a filter 350 b forvertical deblocking of horizontal edges. Filter 350 a is applied to thereconstructed signal S′ being the output of adder 140. The output offilter 350 b, i.e. an image with deblocked vertical edges as denoted S″and input into filter 350 b. The output signal of filter 350 b, i.e. avertically and horizontally deblocked image, and has been denoted S′″.Moreover, FIG. 3 explicitly shows the quantization parameter QP to beinput into entropy encoder 190, horizontal deblocking filter 350 a andvertical deblocking filter 350 b.

The remaining blocks of FIG. 3 correspond to respective blocks of FIG.1, and like features have been denoted by the same reference numerals inFIG. 3 and FIG. 1. In FIG. 3, the adapted loop filter 160 has beenexplicitly described as a Wiener filter, and the blocks 155 (SAO) and160 (ALF) have been interchanged. The sequence of these steps is,however, not essential for the present disclosure. Moreover, referenceframe buffer 170 has not been explicitly shown in FIG. 3.

In view of the close analogy of the respective features of the encoderof FIG. 1 and the decoder of FIG. 2, a person skilled in the art isaware of how to modify FIG. 2 in order to illustrate a decoder whereinhorizontal and vertical deblocking in two subsequent steps is madeexplicit. A respective figure has therefore been omitted herein.

When compressing and decompressing an image, the blocking artifacts aretypically the most annoying artifacts for the user. The deblockingfiltering helps to improve the perceptual experience of the user bysmoothing the edges between the blocks in the reconstructed image. Oneof the difficulties in deblocking filtering is to correctly decidebetween an edge caused by blocking due to the application of a quantizerand between edges which are part of the coded signal. Application of thedeblocking filter is only desirable if the edge on the block boundary isdue to compression artifacts. Iii other cases, by applying thedeblocking filter, the reconstructed signal may be despaired, distorted.Another difficulty is the selection of an appropriate filter fordeblocking filtering. Typically, the decision is made between severallow pass filters with different frequency responses resulting in strongor weak low pass filtering. In order to decide whether deblockingfiltering is to be applied and to select an appropriate filter, imagedata in the proximity of the boundary of two blocks are considered.

For instance, quantization parameters of the neighboring blocks may beconsidered. Alternatively or in addition, prediction modes such as intraor inter may be considered. Another possibility is to evaluatedquantized prediction error coefficients, for instance, how many of themare quantized to zero. Reference frames used for the motion compensatedprediction may also be indicative for selection of the filter, forinstance, whether the same reference frames are used for prediction ofthe current block and the neighboring blocks. The decision may also bebased on motion vectors used for the motion compensated prediction andon whether the motion vectors for the current block and for theneighboring blocks are the same or better they defer. The decision mayinvolve spatial positions of the samples such as distance to the blockpatch.

For instance, H.264/MPEG-4 AVC evaluates the absolute values of thefirst derivation (derivative) in each of the two neighboring blocks, theboundary of which is to be deblocked. In addition, absolute values ofthe first derivative across the edge between the two blocks areevaluated, as described, for instance in H.264/MPEG-4 AVC standard,Section 8.7.2.2. A similar approach is also described in US 2008/0025632A1. The decision is taken for all pixels to be filtered based on thesame criterion and the selection is performed for the entire block. HEVCemploys a similar mechanism, however, uses also a second derivative.

According to these approaches, for actual deblocking, a decision as towhether to deblock is taken for all edges of a block potentially to bedeblocked. Further, if deblocking is enabled, for each individual line,a decision is taken with respect to the kind of filter to be applied.These decisions are taken based on non-deblocked pixel samples.Therefore, the decisions for both deblocking directions have to be takenbefore actually applying the deblocking filters the for both thehorizontal filtering of vertical edges and the vertical filtering ofhorizontal edges. The result is a delay of the first deblocking filterto be applied (for instance, horizontal filtering). In addition, theresult of the filter on/filter off decision needs to be stored.Alternatively, additional line memory would be required in order todelay the decision taking for deblocking in the second direction (forinstance, vertical). Since line memory is very expensive, this resultsin increased cost.

Given the existence of these problems with the existing technology, itwould be advantageous to provide an efficient deblocking filteringapproach wherein the efficiency of memory usage is improved. Accordingto an exemplary embodiment disclosed herein, a method for deblockingfiltering of image blocks of pixels, comprising the steps of: dividingeach of a first and a second block that are separated by a firstboundary into at least two segments along a line that is perpendicularto said first boundary, and judging whether or not to apply a deblockingfilter to pixels adjacent to the first boundary of the first and thesecond block, wherein the judgment is individually performed for a pairof adjacent segments on both sides of the first boundary using samplepixels in the pair of adjacent segments, such that no pixels belongingto other segments are used in the judgment, and the division of theblocks into segments is performed such that a segment of a blockincludes all pixels of the block required for judging whether or not toapply a deblocking filter and/or a selection of the deblocking filterfor deblocking pixels adjacent to a second boundary between said blockand a third block, wherein the second boundary is perpendicular to thefirst boundary.

It is the particular approach of the present disclosure to perform thedecision on whether to apply or skip the deblocking filter for aboundary between two blocks based on a segmentation of each block intoat least two segments along a line that is perpendicular to the blockboundary, rather than based on complete blocks. The segments are definedin such a way that a segment includes all those pixels which are storedanyway since they are needed for the decision on whether to apply orskip the deblocking filtering and/or the selection of an appropriatefilter for another block boundary in a perpendicular direction, adjacentto the respective segment.

According to an aspect of the present disclosure, a method is providedfor deblocking filtering of image blocks of pixels. The method comprisesthe steps of dividing each of a first and a second block that areseparated by first boundary into at least two segments along a line thatis perpendicular to the first boundary, and judging whether or not toapply a deblocking filter to pixels adjacent to the first boundary ofthe first and the second block. The judgment is individually performedfor a pair of adjacent segments on both sides of the first boundaryusing sample pixels in the pair of adjacent segments, such that nopixels belonging to other segments are used in the judgment. Thedivision of the blocks into segments is performed in such a way that asegment of a block includes all pixels of the block required for judgingwhether or not to apply a deblocking filter and/or a selection of thedeblocking filter for deblocking pixels adjacent to a second boundarybetween said block and a third block, wherein the second boundary isperpendicular to the first boundary.

According to another aspect of the present disclosure, a device isprovided for deblocking filtering of image blocks of pixels. The devicecomprises a segmentation unit for dividing each of a first and a secondblock that are separated by the first boundary into at least twosegments along a line that is perpendicular to the first boundary. Thedevice further comprises a judging unit for judging whether or not toapply a deblocking filter to pixels adjacent to the first boundary ofthe first and the second block. The judging unit performs the judgmentindividually for a pair of adjacent segments on both sides of the firstboundary using sample pixels in the pair of adjacent segments, in such away that no pixels belonging to other segments are used in the judgment.The segmentation unit performs the division of the blocks into segmentsso that a segment of a block includes all pixels of the block requiredfor judging whether or not to apply a deblocking filter and/or aselection of the deblocking filter for deblocking pixels adjacent to asecond boundary between the block and a third block, wherein the secondboundary is perpendicular to the first boundary.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Hereinafter, certain exemplary embodiments are described in greaterdetail with reference to the accompanying Drawings.

Each of the exemplary embodiments described below shows a general orspecific example. The numerical values, shapes, materials, structuralelements, the arrangement and connection of the structural elements,steps, the processing order of the steps etc. shown in the followingexemplary embodiments are mere examples, and therefore do not limit thescope of the appended Claims and their equivalents. Therefore, among thestructural elements in the following exemplary embodiments, structuralelements not recited in any one of the independent claims are describedas arbitrary structural elements.

Embodiment 1

The problem underlying the present disclosure is based on theobservation that the conventional decision techniques require anexcessive memory capacity in order to perform all decisions and theactual filtering processing in the desired order, as will be detailedbelow. In order to decrease memory cost, in accordance with the presentdisclosure, a segmentation of the blocks for performing the decisionprocessing is performed, so as to minimize MIC memory requirements. Inaccordance with a further particular aspect, a decreasing overallcalculation complexity is further addressed.

FIG. 4 shows an example of an application of a de-blocking filter (such150, 250, 350 a and 350 b) referred to in the description of FIGS. 1, 2and 3, respectively. Such a deblocking filter may decide for each sampleat a block boundary whether it is to be filtered or not. When it is tobe filtered, a low pass filter is applied. The aim of this decision isto filter only those samples, for which the large signal change at theblock boundary results from the quantization applied in the block-wiseprocessing as described in the background art section above. The resultof this filtering is a smoothed signal at the block boundary. Thesmoothed signal is less annoying to the viewer than the blockingartifact. Those samples, for which the large signal change at the blockboundary belongs to the original signal to be coded, should not befiltered in order to keep high frequencies and thus the visualsharpness. In the case of wrong decisions, the image is eitherunnecessarily smoothened or remains blocky.

FIG. 4A illustrates decision on a vertical boundary (to filter or not tofilter with a horizontal deblocking filter) and FIG. 4B illustratesdecision on a horizontal boundary (to filter or not with a verticaldeblocking filter). In particular, FIG. 4A shows a current block 340 tobe decoded and its already decoded neighboring blocks 310, 320, and 330.For the pixels 360 in a line, the decision is performed. Similarly, FIG.4B shows the same current block 340 and decision performed for thepixels 370 in a column.

The judgment on whether to apply the deblocking filter may be performedas follows, similarly to H.264/MPEG-4 AVC. Let us take a line of sixpixels 360, the first three pixels p2, p1, p0 of which belong to a leftneighboring block A 330 and the following three pixels q0, q1, and q2 ofwhich belong to the current block B 340 as also illustrated in FIG. 5.Line 410 illustrates a boundary between the blocks A and B. Pixels p0and q0 are the pixels of the left neighbor A and of the current block B,respectively, located directly adjacent to each other. Pixels p0 and q0are filtered by the deblocking filtered for instance, when the followingconditions are fulfilled:

|p ₀ −q ₀|<α_(H264)(QP_(New)),

|p ₁ −p ₀|<β_(H264)(QP_(New)), and

|q ₁ −q ₀|<β_(H264)(QP_(New)),

wherein, in general, β_(H264)(QP_(New))<α_(H264)(QP_(New)). Theseconditions aim at detecting whether the difference between p0 and q0stems from blocking artifacts. They correspond to evaluation of thefirst derivation within each of the blocks A and B and between them.

Pixel p1 is filtered if, in addition to the above three conditions, alsothe following condition is fulfilled:

|p ₂ −p ₀|<β_(H264)(QP_(New)).

Pixel q1 is filtered, for instance, if in addition to the above firstthree conditions also the following condition is fulfilled:

|q2−q ₀|<β_(H264)(QP_(New)).

These conditions correspond to a first derivation within the first blockand a first derivation within the second block, respectively. In theabove conditions, QP denotes quantization parameter indicating theamount of quantization applied, and β,α are scalar constants. Inparticular, QP_(New) is quantization parameter derived based onquantization parameters QP_(A) and QP_(B) applied to the respectivefirst and second block A and B as follows:

QP_(New)=(QP_(A)+QP_(B)+1)>>1,

wherein “>>n” denoted right shift by n bits (in the above formula: onebit).

The above conditions correspond to evaluating of the first derivativewithin the blocks. The decision may be performed only for a selectedline or selected lines of a block, while the filtering of pixelsaccordingly is then performed for all lines 360. An example 420 of lines430 involved in decision in compliance with HEVC is illustrated in FIG.5. Based on lines 430, the decision whether to filter entire block iscarried out.

Another example of deblocking filtering in HEVC can be found inJCTVC-E603 document, Section 8.6.1, of JTC-VC, of ITU-T SG16 WP3 andISO/IEC JTC1/SC29/WG11, freely available underhttp://wftp3.itu.int/av-arch/jctvc-site/.

Accordingly, in HEVC the two lines 430 are used to decide whether andhow the deblocking filtering is to be applied. This decision step islabeled first decision step D1 throughout this specification. Theexample 420 assumes the evaluating of the third (with index 2) and thesixth (with index 5) line for the purpose of horizontally blockingfiltering. In particular, the second derivative within each of theblocks is evaluated resulting in the obtaining of measures d_(p) andd_(q) as follows:

d _(p2) =|p2₂−2·p1₂ +p0₂ | d _(q2) =|q2₂−2·q1₂ +q0₂|

d _(p5) =p2₅−2·p1₅ +p0₅ | d _(q5) =q2₅−2·q1₅ +q0₅|

d _(p) =d _(p2) +d _(p5) d _(q) =d _(q2) +d _(q5),

The pixels p belong to block A and pixels q belong to block B. The firstnumber after p or q denotes column index and the following number insubscript denotes row number within the block. The deblocking for alleight lines illustrated in the example 420 is enabled when the followingcondition is fulfilled:

d=d _(p) +d _(q)<β(QP).

If the above condition is not fulfilled, no deblocking is applied. Inthe case that deblocking is enabled, the filter to be used fordeblocking is determined in a subsequent decision step labeled seconddecision step D2 throughout the present specification. Thisdetermination is based on the evaluation of the first derivative betweenthe blocks A and B. In particular, for each line i, wherein i is aninteger between 0 and 7, it is decided whether a strong or a weak lowpass filter is to be applied. A strong filter is elected if thefollowing condition is fulfilled.

|p3_(i) −p0_(i) |+|q3_(i) −q0_(i)|<(β(QP)>>3̂

d<(β(QP)>>2)̂

|p0_(i) −q0_(i)|<((t _(c)(QP)·5+1)>>1).

In compliance with the HEVC model “the strong filter” filters samplesp2_(i), p1_(i), p0_(i), q0_(i), q1_(i), q2_(i) using p3_(i), p2_(i),p1_(i), p0_(i), q0_(i), q1_(i), q2_(i), q3_(i), whereas a “weak filter”filters samples p1_(i), p0_(i), q0_(i), q1_(i), using p2_(i), p1_(i),p0_(i), q0_(i), q1_(i), q2_(i). In the above conditions, parameters βand t_(c) are both functions of the quantization parameter QP_(e) whichmay be set for a slice of the image or the like. The values of β andt_(c) are typically derived based on QP using lookup tables.

FIG. 6 explains in more detail exemplary solutions for strong filteroperations and weak filter operations in compliance with the H264/MPEG-4AVC standard (implemented in HEVC software model HM4.0).

In FIG. 6A the left hand drawing illustrates the samples used forhorizontally filtering a vertical edge in a strong filter. The righthand drawing of FIG. 6A illustrates the samples that are modified by thefilter. As can be seen from the drawing, in the given example samplescorresponding to the 4 pixels most adjacent to both sides of theboundary, denoted by reference numeral 610, are used for the filtering.Actually modified are only those 3 pixels closest to the boundary fromboth sides denoted by 620 in the left hand drawing of FIG. 6A. Actually,filtering is performed in accordance with the following formulae.

p0′_(i)=Clip((p2_(i)+2·p1_(i)+2·p0_(i)+2·q0_(i) +q2_(i)+4)>>3)

p1′_(i)=Clip((p2_(i) +p1_(i) +p0_(i) +q0_(i)+2)>>2)

p2′_(i)=Clip((2·p3_(i)+3·p2_(i) +p1_(i) +p0_(i) +q0_(i)+4)>>3)

q0′_(i)=Clip((q2_(i)+2·q1_(i)+2·q0_(i)+2·p0_(i) +p2_(i)+4)>>3)

q1′_(i)=Clip((q2_(i) +q1_(i) +p0_(i)+2)>>2)

q2′_(i)=Clip((2·q3_(i)+3·q2_(i) +q1_(i) +q0_(i) +p0_(i)+4)>>3)

The function Clip(x) is defined as follows:

${{Clip}(x)} = \left\{ \begin{matrix}{0;} & {x < 0} \\{{{max\_ allowed}{\_ value}};} & {x > {{max\_ allowed}{\_ value}}} \\{x;} & {else}\end{matrix} \right.$

Hereby, max_allowed_value is a maximum value, which x can have. In thecase of PCM coding with k bit samples, the maximum value would bemax_allowed_value=2^(k)−1. For instance, in the case of PCM coding with8 bit samples, the maximum value would be max_allowed_value=255. In thecase of PCM coding with 10 bit samples, the maximum value would bemax_allowed_value=1023.

As can be seen from the above equations, filtering is performedindividually for each line (only a single line index i=0, 1, 2, 3, 4, 5,6, or 7) is employed in each of the formulae where pixels are modifiedby a filter (indicated by a prime ′ after the filter number). While nomodified pixels are calculated for p3_(i) and q3_(i), respectively, itcan be seen from the equations for p2′_(i) and q2′_(i), respectivelythat p3_(i) and q3_(i) occur on the right hand sides of the respectivecalculation equations.

As can be seen from FIG. 6B, the three closest pixels to the boundaryfrom both sides are used for filtering by the weak filter (samples 630in the left hand side scheme). Actually modified are the only the twoclosest neighbours to the boundary (samples 640 on the right hand sideof FIG. 6B. The calculation processing for the weak filteringsubstantially differs from the calculation in the case of strongfiltering and includes further decisions. Firstly, a discriminationvalue Δ is calculated according to equation

Δ=(9·(q0_(i) −p0_(i))−3·(q1_(i) −p1_(i))+8)>>4

on which the decisions are based.

Subsequently in a third decision step D3 it is decided whether toperform filtering at all. In accordance with the third decision,filtering is only applied to pixel samples 640, if the condition|Δ|<10·t_(c) is fulfilled.

In the case that the condition is fulfilled, the closest pixels to theboundary on both sides are filtered in accordance with equations

p0′_(i)=Clip(p0_(i)+Δ₁) q0′_(i)=Clip(q0_(i)−Δ₁), wherein

Δ₁=Clip3(−t _(c) ,t _(c),Δ)

The function Clip(x) is defined as above. The function Clip3(x) isdefined as follows:

${{Clip}\; 3\left( {x,a,b} \right)} = \left\{ \begin{matrix}{a;} & {x < a} \\{b;} & {x > b} \\{x;} & {else}\end{matrix} \right.$

After filtering samples p0 and q0, a fourth decision D4 is performed asto whether to also filter the next closest pixel samples from theviewpoint of the boundary, p1_(i) and q1_(i). The fourth decision D4 isperformed separately for both sides of the boundary, i.e. for the pixelsp1_(i) belong to block A of FIG. 6B and pixels q1_(i) of block B of FIG.6B.

The fourth decision for pixels p1_(i) is based on the above introducedparameter d_(p). If the condition d_(p)<(β/6) is fulfilled, filtering isperformed in accordance with p1′_(i)=Clip(p1_(i)+Δ_(2p)), whereinΔ_(2p)=Clip3(−t_(c2),t_(c2),(((p2_(i)+p0_(i)+1)>>1)−p1_(i)+Δ₁)>>1).

Decision D4 for pixels q_(i) of block B is performed if conditiond_(q)<(β/6) is fulfilled. Filtering is performed in accordance withq1′_(i)=Clip(q1_(i)+Δ_(2q)), whereinΔ_(2q)=Clip3(−t_(c2),t_(c2),(((q2_(i)+q0_(i)+1)>>1)−q1_(i)−Δ₁)>>1).

In the foregoing, parameter t_(c2) is defined in compliance witht_(c2)=t_(c)>>1.

It is noted that the foregoing filtering procedure, although describedby way of example for horizontal filtering of vertical edges is equallyapplicable to vertical filtering of horizontal edges by respectivelyinterchanging horizontal and vertical directions and rows with columns.Moreover, throughout the specification, a convention is applied,according to which the term “line” means either column or row.

FIG. 7 is an overall flow chart illustrating the sequence of decisionsteps D1, D2, D3 and D4 for the particular case of 8×8 blocks, i.e.blocks having eight lines to be filtered.

As can be seen from FIG. 7, in step S10 it is decided in a singledecision for all eight lines whether deblocking filtering is applied ornot. If the decision is made not to apply deblocking (filter OFF), theprocessing ends. If deblocking is applied (filter ON), the filteringprocessing is individually performed for each of the lines (indicated bya subscript j, j=1, 2, . . . , 8) for each of the following steps S20_(j) to S45 j. For simplicity, in the following explanation therespective subscript j has been omitted. Firstly, in step S20, it isdecided for each individual line j whether to apply a strong or the weakfilter (decision D2). If it is decided to apply a strong filter, infollowing step S35, a strong filter is applied, as described above withreference to FIG. 6A. In the contrary case, when it is decided to applya weak filter, processing proceeds to further decision step S30, whereindecision D3 is performed for the individual line j. If it is decided notto apply filtering in decision D3, processing ends. In the contrarycase, filtering of the pixels of the respective line j closest to theboundary, p0 and q0, is performed in step S38, as described above withreference to FIG. 6B. Subsequently, in step S40, it is further decidedwhether also p1 and q1 (next closest to the boundary) are to befiltered. If not, the processing ends. If the decision is positive,processing proceeds to step S45, wherein modified pixels p1′ and q1′ arecalculated. Details of the processing of Steps S30, S38, S40 and S45 aredescribed in accordance with the present example in connection with FIG.6B.

FIG. 8 illustrates by way of example the pixel samples used to performthe decisions D1 (i.e. the decision whether or not to apply deblockingat all to a particular boundary between two blocks). The drawing showstwo rows of blocks. In each row, a previous block already decoded 810, acurrent block to be decoded 820 and a next block to be decoded 830 areillustrated. Since decision D1 is performed on the non-deblocked imageblocks, the illustrated samples correspond to signal S′ of FIG. 3.

As described above, the third and sixth lines (labeled 2 and 5) in thefiltering direction perpendicular to the edge to be filtered employedfor decision D1. Specifically, samples 860 a include two columns used toperform decision D1 for deciding whether to filter the boundary betweencurrent block 820 and the block vertically above block 820. Sample 860 billustrates two rows used to perform the decision D1 whether or not tohorizontally filter the vertical edge between current block 820 and nextblock 830. Similarly, sample 860 c illustrates two rows used to performdecision D1 for a boundary between previous block 810 and current block820. As explained above, for performing the decision in each of thesampled lines three pixels are required, counted from each side of theboundary.

FIG. 9 provides an overview of all sample pixels of the non-deblockedsignal S′ used to perform the decisions D2. Since these decisions areperformed line-individually, pixels of all lines that are perpendicularto the respective boundary for which the decision is to be taken, areincluded into samples 960 illustrated in FIG. 9. As explained above,decision D2 requires the first four pixels adjacent to the boundary onboth sides to be evaluated. Samples 960 show the samples used to performthe decisions D2 for the same boundaries, for which FIG. 8 illustratesthe samples used to perform the decisions D1.

In FIG. 10, samples 1060 are illustrated for being used to perform thedecisions D3 for horizontal filtering of vertical edges, i.e. for theboundaries between current block 820 and previous block 810 and nextblock 830, respectively. As explained above, the decision is performedindividually for each line, but only two pixels from each side next tothe boundary are employed for the decision.

FIG. 11 illustrates samples 1160 used to perform the horizontaldeblocking filtering for vertical edges. As can be seen therefrom, andcontrary to FIG. 10, a “depth” of four pixels on both sides of theboundary is required for the filtering itself.

FIG. 12 illustrates the samples 1260 used to perform the decisions D3for vertical filtering of horizontal boundaries. Since said decision isonly to be performed after performing horizontal deblocking of thevertical edges, these samples are selected from horizontally deblockedsignal S″ of FIG. 3. In order to visualize the difference between theblocks of FIG. 12 and the blocks illustrated in the foregoing figures,an apostrophe has been added to the reference numbers of each of theblocks. Hence, the previous, current and next blocks in FIG. 12 havebeen denoted as 810′, 820′ and 830′, respectively.

FIG. 13 illustrates samples 1360 used to perform the actual verticaldeblocking filtering for horizontal edges. Hence, FIG. 13 differs fromFIG. 12 in the same way as FIG. 11 differs from FIG. 10. In particular,four pixels counted from the block boundary are sampled on both sides ofthe boundary.

The following figures, FIGS. 14 to 16 illustrate the pixel samples whichmay be modified (contrary to the pixel samples to be used for thedecision and for performing the filtering). As in the foregoingexamples, a block of 8×8 samples (i.e. eight rows and 8 columns, oreight lines in each direction) is illustrated. However, said block sizeis an example only.

Specifically, FIG. 14 provides an illustration of samples, which may bemodified by the horizontal deblocking of vertical edges. Out of thepixels of eight lines parallel to the boundary to be deblocked for ablock (denoted “8 samples” in the drawing), a maximum of three lines onboth sides of the boundary becomes modified. As a consequence, asequence of six samples close to the boundary becomes modified. Thesesamples are shaded in FIG. 14. Consequently, in an overall 8×8 block,two samples in between the blocks to be modified remain unchanged ineach block.

FIG. 15 illustrates the samples modified by the horizontal deblocking ofvertical edges. Consequently, FIG. 15 basically corresponds to FIG. 14,wherein, however, the shading portions have been rotated by 90°.

FIG. 16 provides an overall illustration of samples modified by eitherthe horizontal or the vertical deblocking. Thus FIG. 16 corresponds toan overlay of FIGS. 14 and 15.

Based on the above explanations, the problem underlying the presentdisclosure will now be detailed by way of example based on FIGS. 17A and17B. The overall idea of solving said problem will be illustrated inFIG. 17C.

It is noted that the block size and consequently the numbers of storedlines and lines to be used to perform the decision is given in thefollowing detailed description by way of example only. The presentinvention is not limited to 8×8 blocks, and consequently the number ofsample pictures is not limited to those detailed below. Other blocksizes, and consequently a different number of samples to be stored andselected, are possible within the framework of the present disclosure,as defined by the appended claims. Also, the present disclosure is notlimited to the example of the horizontal deblocking to be performedfirst detailed in this specification and illustrated in FIG. 3. Ananalog application of the invention to the opposite case of performingvertical deblocking before horizontal deblocking is straightforward.

FIG. 17A basically corresponds to FIG. 9. In addition, reference number1770 indicates a sample of four lines that are required to perform thedecision D2 (strong or weak filter) of the vertical boundary between theblock above current block 820 and current block 820.

As described above, the decisions D1 and D2 are to be performed onnon-deblocked samples. Therefore, these decisions have to be performedas long as non-deblocked signal S′ of FIG. 3 is still available, i.e.before the vertical filtering of the horizontal edges in filter 350 aactually starts. In other words, filtering (in particular: thehorizontal filtering of vertical edges to be performed first inaccordance with the flowchart of FIG. 3) is delayed by decisions D1 andD2, in particular, for the vertical filtering of horizontal edges.Consequently, the samples of four lines indicated by the numeral 1770 inFIG. 17A, each of a length corresponding to the picture width of thenon-deblocked signal required to perform the decision D2 for verticalfiltering are available at the moment of starting the delayed horizontalfiltering at vertical boundaries.

A hardware implementation can be accomplished as follows: Non-deblockedsamples are stored in a line memory, and the decisions D1 and D2 aresubsequently performed for the horizontal filtering of vertical edgesand for the vertical filtering of horizontal edges for the currentblock, using the stored non-deblocked samples. Subsequently, a delayedhorizontal filtering of the vertical edges is performed for the regionincluding the four stored lines.

For this delayed horizontal filtering, however, the result of thepreviously performed corresponding on/off decision D1 is necessary.Consequently, the result of said decision needs to be either stored, orre-calculated. In case said result is not stored, the re-calculation inaccordance with the above described conventional scheme requires samplepixels from a line that does not belong to stored lines 1770. Namely,for the re-calculation of the decision result of decision D1, samplepixels 1760 illustrated in FIG. 17B are required (corresponding tosamples 430 in FIG. 5, i.e. pixels of the third and sixth line (withsubscripts 2 and 5 in FIG. 5). While the sixth line (with subscript 5 inFIG. 5) belongs to the lines which have been stored anyway, this is notthe case for the third line (with subscript 2 in FIG. 5).

Hence, either the decision result of the previously taken decision D1for the delayed horizontal filtering has to be stored or even pixel datafrom an additional line (the upper line of the lines 1760 in FIG. 17B)has to be additionally stored. However, since line memory is veryexpensive, the latter alternative would be associated with higher costs.

Still alternatively, the delay of the vertical filtering could beavoided by the use of additional line memory. Namely, if there are twoline memories, one of which holds the non-deblocked signal and the otherof which holds the horizontally deblocked signal, decisions D1 and D2for the vertical filtering could be postponed. However, since linememory is very expensive, said alternative is even more disadvantageous.

Therefore, in the above described conventional scheme, the problemarises that either the decision result of decision D1, or an additionalline, not included in the stored lines (here: four lines 1770) have tobe stored for a delayed filter operation.

The present invention aims at overcoming the drawback of theconventional approach caused by the storing problem described above.

In accordance with the present disclosure, each block (in the presentexample: a block of eight lines (rows/columns)) is separated in at leasttwo segments. The segmentation is performed in such a way that it ispossible to perform all decisions (D1: on/off and D2: strong/weak) forthe horizontal filtering of vertical edges on the basis of only thestored lines 1770 (necessary for performing the respective decisions forthe vertical filtering of horizontal edges) and independently from otherlines. As a consequence, no decision buffer or additional line memory isrequired any longer for a delayed horizontal filtering of verticaledges.

Said idea is illustrated in FIG. 17C. Namely, by means of segmentationthe decision D1 for delayed horizontal filtering of vertical edges shallbe modified in such a manner that the decision is taken based only onthose samples of the non-deblocked signal S′ included in the dash box1760 a of FIG. 17C. As can be easily seen, all those pixels belong tostored lines 1770.

More specifically, the inventive solution is described with reference toFIG. 17D. Namely, throughout the blocks involved in the horizontalfiltering, segmentation is performed by dividing the block along thehorizontal segmentation line (i.e. a line perpendicular to the boundaryto be deblocked). For the sake of simplicity, in FIG. 17D, segmentationis illustrated only for the upper row of blocks. The dashed segmentationline 1700 divides each block into two segments (sides) in a verticaldirection. Furthermore, the scheme of taking the decision D1 is modifiedin such a way that no samples from the respective other side arerequired for taking decision D1 for horizontal deblocking of verticaledge within the region of one of the segments.

In other words, the decision D1 is no longer taken for the block as awhole, but separately for each segment (side). For taking the decisionon side 1, only samples from side 1 (in particular: the samplesindicated by number 1760 ₁) are used. For taking the decision for theregion of the segment of side 2, only samples on side 2 (in particular:those indicated by number 1760 ₂) are used.

Vice versa, samples situated on side 1 are not used for the decisionsrequired to perform the horizontal filtering of vertical edges on side2, and samples on side 2 are not used for the decisions required toperform the horizontal filtering of vertical edges on side 1.

In particular, consequently, the decision for side 2 can be taken on thebasis of the stored lines 1770, without reference to any non-storedlines. Thus neither storing a previously determined result nor storingan additional line in an expensive line memory is required.

Concerning side 1, a separate decision can be taken at the time when therespective lines are still stored from the vertical deblocking decisionwith respect to the boundary between the other row of blocks in FIG. 17and the next blocks above (not shown in FIG. 17).

An important advantage of the decision scheme in accordance with thepresent disclosure is the limitation of the dependencies in thedeblocking to areas having the size of a block. As a consequence, if thesample areas (blocks) for deciding are appropriately chosen, they can bedeblocked in parallel to each other. It has to be noted that the sampleareas (blocks) for deciding are generally different from the blocks tothe boundaries of which deblocking is applied.

Said advantageous technical effect is illustrated in FIG. 18 (for theexample of 8×8 blocks).

FIG. 18 is generally based on FIG. 17D and shows six 8×8 blocks theblock boundaries of which are to be deblocked. Further in FIG. 18, an8×8 area 1800 has been emphasized by a dashed square. Within said area1800, the samples necessary for deciding for the horizontal deblockingof the vertical edge 1810 are illustrated (in the same manner as, forinstance, samples 1760 ₂ in FIG. 17D by small dashed rectangles). Inaddition, the respective samples for vertical deblocking filtering ofhorizontal edge 1820 within area 1800 are highlighted (small dashedrectangles with vertical orientation).

As can be seen from FIG. 18, all decisions can be made for the 8×8 block1800 without the need to refer to any samples outside said area. Hence,8×8 area (block) 1800 (and the respective blocks shifted by multiples of8 pixels in horizontal and/or vertical direction) are appropriatedeciding blocks for which can be processed by the deblocking filteringin parallel.

Such an advantage cannot be achieved in the conventional deciding andfiltering scheme. As can be seen, for instance, from FIG. 8, in theprevious scheme there is no 8×8 area (block) for which the samples fordeblocking decision are limited to said same area, such that deblockingfiltering decisions can be made independently within said area. Thus,parallelization is prevented by the conventional scheme.

A still more particular explanation of an exemplary solution forperforming decision D1 (deblocking filter on/off) from an eight lineblock segmented into two four line segments will be described below withreference to FIG. 19. FIG. 19A illustrates the on/off decision for thefour line segment on side 1. As can be seen from FIG. 19A, the decisionis taken based on the first line (with subscript 0) and the fourth line(with subscript 3) only. More specifically, the following parameters arecalculated:

d _(p0) =|p2₀−2·p1₀ +p0₀|

d _(p3) =|p2₃−2·p1₃ +p0₃|

d _(p,side1) =d _(p0) +d _(p3)

and

d _(q0) =|q2₀−2·q1₀ +q0₀|

d _(q3) =|q2₃−2·q1₃ +q0₃|

d _(q,side1) =d _(q0) +d _(q3).

The filter is enabled if the following condition is fulfilled:

d _(q,side1) +d _(p,side1)<β.

FIG. 19B illustrates the respective decision taking for side 2, based onsamples 1760 ₂. The respective calculations are:

d _(p4) =|p2₄−2·p1₄ +p0₄|

d _(p7) =|p2₇−2·p1₇ +p0₇|

d _(p,side2) =d _(p4) +d _(p7)

and

d _(q4) =|q2₄−2·q1₄ +q0₄|

d _(q7) =|q2₇−2·q1₇ +q0₇|

d _(q,side2) =d _(q4) +d _(q7)

The filter is enabled if the condition is fulfilled:

d _(q,side2) +d _(p,side2)<β.

As can be seen from the above details, the modification of decision D1,based on block segmentation, results in a slight increase in the overallcomputational expense. Namely, instead of a conventional single on/offdecision for a block of eight lines, requiring 20 operations, the on/offdecision has to be taken twice, for 4 lines, requiring 40 operations.Hence, the number of operations required for taking decision D1 alonehas doubled.

It is therefore preferable to further modify within the presentdisclosure also the implementation of decision D2, i.e. the decision onwhether a strong or weak filter is appropriate to be applied, tocompensate for the increased computation expense.

FIG. 20 illustrates a first specific solution for a modified decisionD2, based on the segmentation in accordance with the present disclosure.As described above, in the conventional example, decision D2 is takenfor each line individually. In contrast, in accordance with the presentdisclosure, an individual decision is taken only for a subset of linesper segment. On the basis of the individual decisions for the subset ofsegments, a single decision of a filter is taken for all lines of thesegment.

More specifically, FIG. 20A shows the modified decision D2 in accordancewith the first specific example for side 1. The decision is based on thefirst line (having subscript 0) and the fourth line (having subscript3), which are indicated by the number 1960 ₁ in FIG. 20A. For each ofthe two lines with the subscripts 0 and 3, the decision between strongand weak filter is performed (preferably in the conventional mannerdescribed above). If for both lines the strong filter is selected, allfour lines (0, 1, 2, 3) are strongly filtered. Otherwise, the weakfilter is selected.

The respective operation scheme on side 2 is illustrated in FIG. 20B.Decision D2 for side 2 is based on the two lines with subscripts 4 and7, indicated with reference numeral 1960 ₂. For each of the two lines 4and 7, the decision between a strong and a weak filter is performed. Iffor both lines the strong filter is selected, all four lines 4, 5, 6, 7are strongly filtered. Otherwise, the weak filter is selected.

A simulation reveals that the coding efficiency according to thedescribed embodiment of the present disclosure is slightly increasedwith respect to the conventional HM 4.0 scheme described above. Thecoding efficiency of the embodiment of the invention described abovewith reference to FIGS. 19 and 20 has been evaluated based on the codingconditions commonly used in the standardization activities of the ISOand the ITU, see document JCTVC-E700(http://phenix.int-evry.fr/jct/doc_end_user/current_document.php?id=2454).The invention leads to an average bit rate reduction of around 0.15% atthe same mean squared quantization error.

Further, on the basis of the modification of both decisions D1 and D2, adecrease in the overall computational expense can also be achieved.Namely, in accordance with the above described conventional scheme, thefollowing overall number of operations is required:

on/off decision for 8 lines: 20 operations

8 strong/weak decisions: 96 operations

sum of computations: 116 operations

According to the illustrated embodiment of the present disclosure, theoverall number of operations is as follows:

2 times on/off decision for 4 lines: 40 operations

4 strong/weak decisions: 48 operations

sum of computations: 96 operations

Consequently, the present disclosure enables decreasing the overallnumber of computations by approximately 20%.

The second exemplary solution of modified decision D2 is similar to thefirst example described above. In the same manner as in the firstexample, on the first side for each of the two lines 0 and 3 thedecision between a strong and a weak filter is performed. If the weakfilter is selected for both lines, all four lines 0, 1, 2, 3 are weaklyfiltered. Otherwise, the strong filter is selected.

In the same manner, on side 2, for each of the two lines 4 and 7, thedecision between a strong and a weak filter is performed. If the weakfilter is selected for both lines, all four lines 4, 5, 6, 7 are weaklyfiltered. Otherwise, the strong filter is selected.

Hence, the second illustrated example differs from the first example inthat in accordance with the second example in case of a discrepancybetween the individual decisions for the two selected lines, the strongfilter is selected, while according to the first example in case of adiscrepancy always the weak filter is selected. Since the computationalcomplexity of the weak filter is generally less than for the strongfilter, the first example enables a further decrease in computationalexpense.

In accordance with a third example, modified decision D2 is alsoperformed on the basis of the selected lines illustrated in FIGS. 20Aand 20B. However, in accordance with the third example, decision D2 iscombined with decision D3. Namely, for each of the selected lines, thecombined decision between a strong filter, a weak filter and no filteris performed. The respective decisions are taken on the basis of alook-up table.

More specifically, on side 1, for each of the two lines 0 and 3, thedecision between a strong filter, a weak filter and no filter isperformed. The two decision results are used to decide for all fourlines 0, 1, 2, 3 by means of the following look-up table.

Resulting decision for Decision for line 0 Decision for line 3 lines 0-3(example) Strong Strong Strong Strong Weak Weak Strong Off Off WeakStrong Weak Weak Weak Weak Weak Off Off Off Strong Off Off Weak Off OffOff Off

On side 2, for each of the two lines 4 and 7, the decision between astrong filter, a weak filter and no filter is performed. The twodecision results are used to decide for all four lines 4, 5, 6, 7 bymeans of the following look-up table.

Resulting decision for Decision for line 4 Decision for line 7 lines 4-7(example) Strong Strong Strong Strong Weak Weak Strong Off Off WeakStrong Weak Weak Weak Weak Weak Off Off Off Strong Off Off Weak Off OffOff Off

As can be seen from the above tables, in case the decisions for the twolines differ, the one of lower complexity is always selected. Thereby,computational expense is further saved.

A fourth example, illustrated with reference to FIG. 21, is generallysimilar to the third example. As can be seen from FIG. 21 on side 1(FIG. 21A the second and third lines with ₁ and ₂) are selected for theindividual decision. On side 2, the sixth and seventh lines (with ₅ and₆) are selected. Corresponding look-up tables are shown below:

Resulting decision for Decision for line 1 Decision for line 2 lines 0-3(example) Strong Strong Strong Strong Weak Weak Strong Off Off WeakStrong Weak Weak Weak Weak Weak Off Off Off Strong Off Off Weak Off OffOff Offand

Resulting decision for Decision for line 5 Decision for line 6 lines 4-7(example) Strong Strong Strong Strong Weak Weak Strong Off Off WeakStrong Weak Weak Weak Weak Weak Off Off Off Strong Off Off Weak Off OffOff Off

It has to be understood that the particular solution of a modifieddecision D2, performed on a segment basis rather than on an individualline basis, is not limited to the four examples given above. Furthermodifications as well as combinations of individual elements of theseexamples are possible within the scope of the present disclosure asdefined by the appended claims. In the above examples, a decision D2 hasbeen based on samples of two lines. The present invention is however notlimited to said number of lines used for selection. The filter selectionmay be based on only a single line or any other number of lines that issmaller than the overall number of lines in the respective pair ofsegments to be deblocked.

In the following, a first memory access problem occurring in taking theon/off decision D1 is described and addressed with respect to FIGS. 22and 23. FIG. 22 illustrates the conventional HEVC approach of takingdecision D1 for horizontal deblocking of a vertical edge.

As indicated in the upper scheme of FIG. 22A, in a first step line 2 isread in the associated decision values d_(p2) and d_(q2) are calculated.In a second step, line 5 is read and the associated decision valuesd_(p5) and d_(u5) are calculated.

In a third step, the decision value d₅=d_(q2)+d_(p2)+d_(q5)+d_(p5) iscalculated, and the on/off decision D1 is performed for all eight lines.The strong/weak filter decision is then performed for line 5, deblockingand writing back of the deblocking result are performed for line 5.

In a subsequent fourth step, for each of the remaining lines, 0, 1, 2,3, 4, 6 and 7 the respective line is read, strong/weak filtering isdecided, deblocking is performed and the result is written back. As aconsequence, the following problem occurs: for deblocking of eightlines, either line 2 or line 5 needs to be read twice: once for thedecision D1 and once for the deblocking. In total, 9 line readingoperations need to be performed, although there are only 8 lines perblock.

Said problem can be advantageously resolved with a modified deblockingscheme as illustrated with reference to FIG. 23. In a first step, line 2(2362) is read and the associated decision values d_(b2) and d_(u2) arecalculated. A modified decision value d₂=2×(d_(d2′)+d_(p2)) iscalculated, and the on/off decision D1 valid for this line is based onthe criterion d₂<β. Subsequently, the strong/weak filter decision D2 isperformed, it is deblocked and the result is written back. In a secondstep, line 5 (2365) is read in the same manner, and the associateddecision values d_(b5) and d_(q5) are computed. The modified decisionvalue d₅=2×(d_(q5)+d_(b5)) is computed, and the on/off decision D1 isperformed based on the criterion d₅<β valid for this line. Strong/weakfilter decision D2 is performed, and deblocking and writing back theresult is individually performed for line 5 (2365).

Subsequently, decision value d=(d₂+d₅)/2 is computed, and theenable/disable decision d<β is performed for remaining lines 0, 1, 3, 4,6 and 7 as illustrated by reference 2360 in FIG. 23B. In the subsequentfourth step, for the remaining lines 0, 1, 3, 4, 6 and 7 the pixelsamples are read, strong/weak filter decision is performed, thedeblocking is then carried out and the result is written back.

In accordance with a modified example of the improved deblocking forsolving the memory access problem, steps 1, 2 and 4 are performed aspreviously described. Step 3 described above is modified in that nocommon decision value d for the remaining lines is computed. To thecontrary, the on/off decision in step 3 for the remaining lines 0, 1, 3,4, 6, 7 is performed on the basis of the decision (d₂<β)&(d₅<β).

More generally speaking, a modified decision scheme for decision D1 isperformed in such a way that decision D1 is not taken for the wholeblock, but separately (individually) for those lines, the pixel samplesof which are used for calculating and applying the decision criterion(in the present example: lines 2 and 5). Subsequently, the decision istaken for the remaining lines.

The decision scheme for each of the lines for which the decision D1 istaken individually has moreover to be modified in such a manner that theused pixel samples are separated, i.e. the individual decision D1 for aparticular line is taken only based on sample pixels from said line. Thedecision scheme for the remaining lines of the block may either be theconventional one such as described above with reference to FIGS. 4 and5, or may be also modified. The decision for the remaining lines may bebased on pixel samples of all those lines for which an individualdecision is taken.

The following advantages are achieved by both versions of the modifieddecision D1: Firstly, each line needs to be read only once, and as aconsequence only a number of line reading operations equal to the numberof lined per block (in the present case: 8) is to be performed.Moreover, a more accurate decision is achieved for those lines for whichthe decision is performed individually (in the present case: lines 2 and5).

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

Embodiment 2

FIG. 24 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 24, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent disclosure), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present disclosure).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 25. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent disclosure). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present disclosure).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300. FIG. 26 illustrates the television (receiver) ex300that uses the moving picture coding method and the moving picturedecoding method described in each of embodiments. The television ex300includes: a tuner ex301 that obtains or provides multiplexed dataobtained by multiplexing audio data onto video data, through the antennaex204 or the cable ex203, etc. that receives a broadcast; amodulation/demodulation unit ex302 that demodulates the receivedmultiplexed data or modulates data into multiplexed data to be suppliedoutside; and a multiplexing/demultiplexing unit ex303 that demultiplexesthe modulated multiplexed data into video data and audio data, ormultiplexes video data and audio data coded by a signal processing unitex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present disclosure); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 27 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight. FIG. 28 illustrates the recording medium ex215 that is theoptical disk. On the recording surface of the recording medium ex215,guide grooves are spirally formed, and an information track ex230records, in advance, address information indicating an absolute positionon the disk according to change in a shape of the guide grooves. Theaddress information includes information for determining positions ofrecording blocks ex231 that are a unit for recording data. Reproducingthe information track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 26. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 29A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 29B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent disclosure), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present disclosure),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably have 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, the present disclosure is not limited to embodiments, andvarious modifications and revisions are possible without departing fromthe scope of the present disclosure.

Embodiment 3

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconform cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG-2 Transport Stream format.

FIG. 30 illustrates a structure of the multiplexed data. As illustratedin FIG. 30, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 31 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 32 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 32 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 32, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 33 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 33. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers include in the multiplexed data, and attribute information of thestreams corresponding to the PIDs. The PMT also has various descriptorsrelating to the multiplexed data. The descriptors have information suchas copy control information showing whether copying of the multiplexeddata is permitted or not. The PCR stores STC time informationcorresponding to an ATS showing when the PCR packet is transferred to adecoder, in order to achieve synchronization between an Arrival TimeClock (ATC) that is a time axis of ATSs, and an System Time Clock (STC)that is a time axis of PTSs and DTSs.

FIG. 34 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 35. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 35, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 36, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 37 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by the movingpicture decoding method in each of embodiments. Furthermore, when thestream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present embodiment can be used inthe devices and systems described above.

Embodiment 4

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 38 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present disclosureis applied to biotechnology.

Embodiment 5

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG-4 AVC, and VC-1 is decoded, theprocessing amount probably increases. Thus, the LSI ex500 needs to beset to a driving frequency higher than that of the CPU ex502 to be usedwhen video data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 39illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 38.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 38. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, the identification information described inEmbodiment B is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment B but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 41. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 40 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set higher. When the identification information indicates thatthe video data conforms to the conventional standard, such as MPEG-2,MPEG-4 AVC, and VC-1, the voltage to be applied to the LSI ex500 or theapparatus including the LSI ex500 is probably set lower. As anotherexample, when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, the drivingof the CPU ex502 does not probably have to be suspended. When theidentification information indicates that the video data conforms to theconventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1, the drivingof the CPU ex502 is probably suspended at a given time because the CPUex502 has extra processing capacity. Even when the identificationinformation indicates that the video data is generated by the movingpicture coding method and the moving picture coding apparatus describedin each of embodiments, in the case where the CPU ex502 has extraprocessing capacity, the driving of the CPU ex502 is probably suspendedat a given time. In such a case, the suspending time is probably setshorter than that in the case where when the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 6

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Ex900 in FIG. 42A showsan example of the configuration. For example, the moving picturedecoding method described in each of embodiments and the moving picturedecoding method that conforms to MPEG-4 AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. The details ofprocessing to be shared probably include use of a decoding processingunit ex902 that conforms to MPEG-4 AVC. In contrast, a dedicateddecoding processing unit ex901 is probably used for other processingunique to an aspect of the present disclosure. Since the aspect of thepresent disclosure is characterized by inverse quantization inparticular, for example, the dedicated decoding processing unit ex901 isused for inverse quantization. Otherwise, the decoding processing unitis probably shared for one of the entropy decoding, deblockingfiltering, and motion compensation, or all of the processing. Thedecoding processing unit for implementing the moving picture decodingmethod described in each of embodiments may be shared for the processingto be shared, and a dedicated decoding processing unit may be used forprocessing unique to that of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 42B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present disclosure, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present disclosure and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentdisclosure and the processing of the conventional standard,respectively, and may be the ones capable of implementing generalprocessing. Furthermore, the configuration of the present embodiment canbe implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present disclosure and the moving picturedecoding method in conformity with the conventional standard.

In summary, the present disclosure relates to deblocking filtering,which may be advantageously applied for block-wise encoding and decodingof images or video signals. In particular, the present disclosurerelates to an improved memory management in an automated decision onwhether to apply or skip deblocking filtering for a block and toselection of the deblocking filter. The decision is performed on thebasis of a segmentation of blocks in such a manner that memory usage isoptimized. Preferably, the selection of appropriate deblocking filtersis improved so as to reduce computational expense.

Each of the structural elements in each of the above-describedembodiments may be configured in the form of an exclusive hardwareproduct, or may be realized by executing a software program suitable forthe structural element. Each of the structural elements may be realizedby means of a program executing unit, such as a CPU and a processor,reading and executing the software program recorded on a recordingmedium such as a hard disk or a semiconductor memory. Here, the softwareprogram for realizing the method for deblocking filtering of imagesaccording to each of the embodiments is a program described below.

The program causes a computer to execute dividing each of a first and asecond block that are separated by a first boundary into at least twosegments along a line that is perpendicular to said first boundary, andjudging whether or not to apply a deblocking filter to pixels adjacentto the first boundary of the first and the second block, wherein thejudgment is individually performed for a pair of adjacent segments onboth sides of the first boundary using sample pixels in the pair ofadjacent segments, such that no pixels belonging to other segments areused in the judgment, and the division of the blocks into segments isperformed such that a segment of a block includes all pixels of theblock required for judging whether or not to apply a deblocking filterand/or a selection of the deblocking filter for deblocking pixelsadjacent to a second boundary between said block and a third block,wherein the second boundary is perpendicular to the first boundary.

The herein disclosed subject matter is to be considered descriptive andillustrative only, and the appended Claims are of a scope intended tocover and encompass not only the particular embodiments disclosed, butalso equivalent structures, methods, and/or uses.

INDUSTRIAL APPLICABILITY

A method and apparatus for deblocking filtering according to one aspectof the present disclosure is applicable to, for example, televisionreceivers, digital video recorders, car navigation systems, mobilephones, digital cameras, and digital video cameras.

1. A method for deblocking filtering of image blocks of pixels,comprising the steps of: dividing each of a first and a second blockthat are separated by a first boundary into at least two segments alonga line that is perpendicular to said first boundary, and judging whetheror not to apply a deblocking filter to pixels adjacent to the firstboundary of the first and the second block, wherein the judgment isindividually performed for a pair of adjacent segments on both sides ofthe first boundary using sample pixels in the pair of adjacent segments,such that no pixels belonging to other segments are used in thejudgment, and the division of the blocks into segments is performed suchthat a segment of a block includes all pixels of the block required forjudging whether or not to apply a deblocking filter and/or a selectionof the deblocking filter for deblocking pixels adjacent to a secondboundary between said block and a third block, wherein the secondboundary is perpendicular to the first boundary.
 2. The method accordingto claim 1, wherein said judging step is based on the amount ofquantization of the first block and the amount of quantization of thesecond block.
 3. The method according to claim 1, further comprising astep of selecting from a plurality of deblocking filters a deblockingfilter to be applied to pixels of all lines of said pair of adjacentsegments, the lines being perpendicular to the first boundary, in casethe individual judgment is positive for said pair of segments.
 4. Themethod according to claim 3, wherein the step of selecting including thesteps of individually deciding a deblocking filter to be selected foreach of a number N of said lines, wherein N is at least one and N issmaller than the overall number of lines in the pair of segments; andselecting the single deblocking filter for all lines of the pair ofsegments in accordance with a predetermined rule based on the results ofsaid individual decisions.
 5. The method according to claim 1, furthercomprising a step of either selecting from a plurality of deblockingfilters a deblocking filter to be applied to pixels of all lines of saidpair of adjacent segments, the lines being perpendicular to the firstboundary, or deciding that no deblocking filter is applied, in case theindividual judgment is positive for said pair of segments.
 6. The methodaccording to claim 5, wherein the step of selecting or decidingincluding the steps of individually deciding a deblocking filter to beselected or deciding that no deblocking filter is to be applied for eachof a number N of said lines, wherein N is at least one and N is smallerthan the overall number of lines in the pair of segments; and selectingthe single deblocking filter or deciding that no deblocking filter isapplied for all lines of the pair of segments in accordance with apredetermined rule based on the results of said individual decisions. 7.The method according to claim 6, wherein the predetermined rule definesthat no deblocking filter is applied if at least the individual decisionfor one line has the result not to apply a deblocking filter, and thepredetermined rule defines to select the deblocking filter requiring theleast complexity of processing effort out of plural different deblockingfilters resulting from the individual decision steps otherwise.
 8. Themethod according to claim 4, wherein said judging step is based on pixelsamples of the same N lines, on which said selecting and/or decidingstep is based.
 9. The method according to claim 1, wherein the said twosegments are of the same size.
 10. The method according to claim 9,wherein the said two segments are each of the size of four lines. 11.The method according to claim 4, wherein the said two segments are eachof the size of four lines and N is equal to two.
 12. The methodaccording to claim 4, wherein N is equal to two and the predeterminedrule defines to select a strong filter for all lines of the pair ofsegments if a strong filter is decided in said individual decisions forboth of said lines for which the individual decision is performed, anddefines to select a weak filter for all lines of the pair of segmentsotherwise.
 13. A method for encoding a current block of an imageincluding a plurality of pixels, the method comprising the steps of:compressing and reconstructing the current block, and applying all stepsaccording to claim 1 to the reconstructed block.
 14. A method fordecoding a coded current block of an image including a plurality ofpixels, the method comprising the steps of: reconstructing the codedcurrent block, and applying all steps according to claim 1 to thereconstructed block.
 15. A computer program product comprising acomputer-readable medium having a computer-readable program codeembodied thereon, the program code being adapted to carry out the methodaccording to claim
 1. 16. An apparatus for deblocking filtering of imageblocks of pixels comprising: a segmentation unit for dividing each of afirst and a second block that are separated by a first boundary into atleast two segments along a line that is perpendicular to said firstboundary, and a judging unit for judging whether or not to apply adeblocking filter to pixels adjacent to the first boundary of the firstand the second block, wherein the judging unit performs the judgmentindividually for a pair of adjacent segments on both sides of the firstboundary using sample pixels in the pair of adjacent segments, such thatno pixels belonging to other segments are used in the judgment, and thesegmentation unit performs the division of the blocks into segments suchthat a segment of a block includes all pixels of the block required forjudging whether or not to apply a deblocking filter and/or a selectionof the deblocking filter for deblocking pixels adjacent to a secondboundary between said block and a third block, wherein the secondboundary is perpendicular to the first boundary.
 17. The apparatusaccording to claim 16, wherein said judgment is based on the amount ofquantization of the first block and the amount of quantization of thesecond block.
 18. The apparatus according to claim 16, furthercomprising a selecting unit for selecting from a plurality of deblockingfilters a deblocking filter to be applied to pixels of all lines of saidpair of adjacent segments, the lines being perpendicular to the firstboundary, in case the individual judgment by the judging unit ispositive for said pair of segments, and a filtering unit for applyingthe selected deblocking filter.
 19. The apparatus according to claim 18,wherein the selecting unit including a deciding section for individuallydeciding a deblocking filter to be selected for each of a number N ofsaid lines, wherein N is at least one and N is smaller than the overallnumber of lines in the pair of segments; and the selection of the singledeblocking filter for all lines of the pair of segments is performed inaccordance with a predetermined rule based on the results of saidindividual decisions.
 20. The apparatus according to claim 16, furthercomprising a filter deciding unit for either selecting from a pluralityof deblocking filters a deblocking filter to be applied to pixels of alllines of said pair of adjacent segments, the lines being perpendicularto the first boundary, or deciding that no deblocking filter is applied,in case the individual judgment by the judging unit is positive for saidpair of segments, and a filtering unit for applying the selecteddeblocking filter.
 21. The apparatus according to claim 20, wherein thefilter deciding unit individually decides a deblocking filter to beselected or deciding that no deblocking filter is to be applied for eachof a number N of said lines, wherein N is at least one and N is smallerthan the overall number of lines in the pair of segments; and selectsthe single deblocking filter or deciding that no deblocking filter isapplied for all lines of the pair of segments in accordance with apredetermined rule based on the results of said individual decisions.22. The apparatus according to claim 21, wherein the predetermined ruledefines that no deblocking filter is applied if at least the individualdecision for one line has the result not to apply a deblocking filter,and the predetermined rule defines to select the deblocking filterrequiring the least complexity of processing effort out of pluraldifferent deblocking filters resulting from the individual decisionsteps otherwise.
 23. The apparatus according to claim 19, wherein saidjudgment by the judging unit is based on pixel samples of the same Nlines, on which said decision by the deciding section is based.
 24. Theapparatus according to claim 21, wherein said judgment by the judgingunit is based on pixel samples of the same N lines, on which saiddecision by the filter deciding unit is based.
 25. The apparatusaccording to claim 16, wherein the said two segments are of the samesize.
 26. The apparatus according to claim 25, wherein the said twosegments are each of the size of four lines.
 27. The apparatus accordingto claim 21, wherein the said two segments are each of the size of fourlines and N is equal to two.
 28. The apparatus according to claim 21,wherein N is equal to two and the predetermined rule defines to select astrong filter for all lines of the pair of segments if the filterdeciding unit decides a strong filter in said individual decisions forboth of said lines for which the individual decision is performed, anddefines to select a weak filter for all lines of the pair of segmentsotherwise.
 29. An apparatus for encoding a current block of an imageincluding a plurality of pixels, the apparatus comprising: an encoderwith a decoder for compressing and reconstructing the current block, andthe apparatus according to claim 16 for deblocking filtering thereconstructed block.
 30. An apparatus for decoding a coded current blockof an image including a plurality of pixels, the apparatus comprising: adecoder for reconstructing the coded current block, and the apparatusaccording to claim 16 for deblocking filtering the reconstructed block.31. An integrated circuit for embodying the apparatus of claim 16,further comprising a memory for storing pixels to be filtered.